Advances have been made in mounting of air bags in vehicles, as devices that serve to alleviate impact on the human body during collision accidents of vehicles such as automobiles. Air bags that absorb and alleviate impact on the human body by deploying with gas upon collision continue to be implemented for occupant protection, with installation of curtain air bags or side air bags, knee air bags, rear air bags and the like, in addition to driver seat and passenger seat air bags, in vehicles. Furthermore, for pedestrian protection, air bags have also been proposed that are installed so as to expand out of the vehicle cabin.
Such air bags are normally housed in a small folded state. When an accident impact has been detected by a sensor and the air bag is deployed and expanded, gas generated by an inflator causes the folding to be pushed and spread out, while the cover section of the housing is ripped open and the air bag flies out, receiving the human body at a point where it has sufficiently deployed.
In recent years, there has been a demand for air bags to deploy more rapidly in order to adapt to a wider range of collision conditions. They are therefore being deployed with high-temperature, high-pressure gas, with inflators using propellants with higher output. It is therefore necessary to increase the heat and pressure resistance of the bags, for more highly safe air bags. Another issue, for maintaining long-term performance, is to reduce the high-pressure air permeability after exposure to heat.
Patent Document 1 describes an air bag woven fabric having a resin coating film, the coating being with a specific resin composition, whereby the melting point increases as measured with a differential scanning calorimeter, and damage is avoided during high-temperature deployment of the air bag. In order to suppress air permeability it is effective to employ a method of providing a resin coating film on the fabric, but for more high-speed deployment, it is advantageous to use a lightweight woven fabric without a resin coating film.